Interconnect including a pliable surface and use thereof

ABSTRACT

The present invention provides an interconnect. The interconnect comprises a pliable surface having a plurality of nanostructures disposed thereon, the pliable surface configured to allow the plurality of nanostructures to at least partially conform to a surface when the nanostructures come into contact therewith.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a continuation-in-part of U.S. application Ser. No.10/816,527 filed on Apr. 1, 2004, entitled A HIGH DENSITY NANOSTRUCTUREDINTERCONNECTION, @ commonly assigned with the present invention andincorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention is directed, in general, to an interconnectincluding a pliable surface and method of use thereof.

BACKGROUND OF THE INVENTION

Methods for electrically or thermally connecting electronics componentsonto, for example, a conductor or semiconductor substrate, are wellknown in the art. For example, both thermo-compression and solder bumpbonding methods have been used to create connections between,illustratively, components in optoelectronic devices and/ormicroelectromechanical (MEMS) devices. FIG. 1 shows one illustrativemethod of forming a thermo-compression bond for use as a thermal orelectrical interconnection. Specifically, in that FIGURE, component 110has a layer of a material 120, typically gold, which is suitable forcompression bonding. In order to bond component 110 with illustrativesubstrate 150, layer 120 on component 110 is, for example, lowered indirection 140 in a way such that it is brought into contact with a layer130 of material, once again illustratively gold, on substrate 150. Asufficient temperature (e.g., 300 degrees Celsius) and pressure (e.g.,10 kgf/mm² of gold area) are applied such that the gold layers deformand bond together. However, while such gold-gold thermo-compressionbonding is useful in many regards, the temperatures and pressuresrequired to create such a bond may damage sensitive electronic elements,such as transistors. As components become smaller and smaller (e.g., inMEMS devices), relatively high temperatures and pressures become morelikely to cause damage to the increasingly fragile components.

FIG. 2 depicts another conventional method of thermally or electricallyconnecting two electronic components. Specifically, in that FIGURE,substrate 210 is, for example, a surface of an electronics chip such asa microprocessor in a MEMS package. Solder bumps 220 are created on thechip using well-known methods. In order to create an electrical orthermal connection between the chip and a substrate, such as a printedwire board, the solder bumps 220 are brought into contact withconnection points and are then heated until they reflow. The bumps arethen brought into contact with connection points on the exemplaryprinted wire board. Such solder bump methods are well-known as beingvery advantageous in forming electrical and thermal connections.However, once again, the temperature necessary to reflow the solder maydamage components in the package. Additionally, solder bumps have beenlimited by certain design considerations. Specifically, such bumps mustbe above a certain size, typically larger than 20-25 microns indiameter, in order to achieve the desired bump height. Additionally,since it is undesirable to have solder bumps come into contact with oneanother when the solder is reflowed, solder bumps must typically beseparated by a minimum distance, for example, 50 microns from the centerof one bump to the center of an adjacent bump.

Finally, one other prior method for bonding two components together isto use a thermally and/or electrically conducting adhesive. However,such adhesives are typically subject to out-gassing as they cure, whichmay introduce damaging organic material on critical optical devices(e.g., lasers, detectors, etc.) and MEMS components that can interferewith proper performance of small components.

Embodiments of the present invention provide an improved bond and amethod of manufacture therefore, whether it is thermal, electrical orotherwise, that substantially reduces the problems associated with theabove-mentioned bonds.

SUMMARY OF THE INVENTION

To address the above-discussed deficiencies of the prior art, thepresent invention provides an interconnect. The interconnect comprises apliable surface having a plurality of nanostructures disposed thereon,the pliable surface configured to allow the plurality of nanostructuresto at least partially conform to a surface when the nanostructures comeinto contact therewith.

The present invention further provides a method for interconnectingmultiple surfaces. The method comprises contacting a plurality ofnanostructures disposed on a pliable surface with a surface, wherein thepliable surface is configured to allow the plurality of nanostructuresto at least partially conform to the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read with the accompanying FIGUREs. It is emphasized that, inaccordance with the standard practice in the semiconductor industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbotrarily increased or reduced for clarity ofdiscussion. Reference is now made to the following descriptions taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a conventional method of forming a thermo-compressionbond for use as a thermal or electrical interconnection;

FIG. 2 illustrates another conventional method of thermally orelectrically connecting two electronic components; and

FIGS. 3-8 illustrate cross-sectional views of embodiments of aninterconnect constructed in accordance with the principles of thepresent invention.

DETAILED DESCRIPTION

The present invention is based, at least in part, on the recognitionthat nanostructures may, advantageously, be used to couple two or moresurfaces together, whether it be physically, electrically, thermally orany combination thereof. Within this recognition is the appreciationthat in order to obtain superior coupling, again whether it isphysically, electrically, thermally or any combination thereof, adesired number of the nanostructures (e.g., a substantial number of thenanostructures) must appropriately contact the opposing surface.

Based upon the aforementioned appreciation, as well as substantialexperimentation, the present invention acknowledges that the degree ofcoupling of the nanostructures to an opposing surface is at leastpartially a function of the surface roughness or one or both of thenanostructures and the opposing surface. For instance, the presentinvention acknowledges that because the nanostructures are themselvescoupled to a rigid surface, they are generally unable to conform to anopposing rough surface when the two are brought together. For similarreasons, nanostructures have their own surface roughness are generallyunable to conform to an opposing surface, whether rough or not. In thosesituations wherein the surface roughness is significant enough, thecoupling of the nanostructures to the opposing surface is compromised.Accordingly, the present invention acknowledges that by forming theplurality of nanostructures on a pliable surface, the pliable surfacewill allow the plurality of nanostructures to at least partially conformto the surface they are to contact.

Turning now to FIG. 3 illustrated is a cross-sectional view of oneembodiment an interconnect 300 constructed in accordance with theprinciples of the present invention. The interconnect 300 illustrated inFIG. 3 includes a first substrate 310. The first substrate 310, amongmany other materials, may comprise a silicon substrate. For instance, inthe embodiment shown, the first substrate 310 is a conventionalsemiconductor chip upon which, or within which, numerous semiconductordevices have been formed.

Formed over the first substrate 310 in the embodiment of FIG. 3 is apliable surface 320. As will be evident further below, the pliablesurface 320 may comprise a variety of different materials and/orconfigurations and remain within the purview of the present invention.In the embodiment of FIG. 3, however, the pliable surface 320 comprise amaterial, such as a polymer, that provides it the flexibility to allowthe plurality of nanostructures 330 formed thereover to at leastpartially conform to a rough surface 340 that it might come into contactwith. One particularly useful polymer that might be used for the pliablesurface 320 illustrated in FIG. 3 is a polymide. Another particularlyuseful polymer material that might be used for the pliable surface 320illustrated in FIG. 3 is a fluoropolymer. Even though a couple ofspecific polymer materials have been provided, the options are abundant,and thus the present invention should not be limited to any specificmaterial.

Disposed on the pliable surface 320 of FIG. 3 is a plurality ofnanostructures 330, here nanoposts. Cylindrical nanopost arrays, such asthose shown in FIG. 3, have been produced with each nanopost having adiameter of less than about 10 nm. One skilled in the art will recognizethat there are many different illustrative arrangements (e.g., sizes,pitch and height) of nanoposts that can be produced using variousmethods, and that such various diameter nanoposts can be fashioned withdifferent degrees of regularity. An illustrative method of producingnanoposts, found in U.S. Pat. No. 6,185,961, titled “Nanopost arrays andprocess for making same,” issued Feb. 13, 2001 to Tonucci, et al., ishereby incorporated by reference herein in its entirety. Nanoposts havebeen manufactured by various methods, such as by using a template toform the posts, by various means of lithography, and by various methodsof etching.

As typically defined, a “nanostructure” is a predefined structure havingat least one dimension of less than about one micrometer and a“microstructure” is a predefined structure having at least one dimensionof less than about one millimeter. However, although the disclosedembodiments only refer to nanostructures, it is intended by the presentinventors, and will be clear to those skilled in the art, thatmicrostructures may be substituted in many cases. Accordingly, thepresent invention hereby defines nanostructures to include bothstructures that have at least one dimension of less than about onemicrometer as well as those structures having at least one dimensionless than about one millimeter.

The nanostructures 330 of FIG. 3 are, for example, posts of a polymermaterial. Accordingly, in those embodiments wherein the pliable surface320 comprises a polymer material, as disclosed above, the nanostructures330 and the pliable surface 320 may comprise the same polymer material.In the embodiment of FIG. 3, the nanostructures have, illustratively, adiameter of about 200 nm and a height of about two micrometers. Thenanostructures 330 are, for example, disposed in an area having across-section width (e.g., which is, illustratively, a circular diameteror a length of a side of a square area) of about 10 micrometers. Oneskilled in the art will also recognize, in light of the teachingsherein, that many suitable arrangements are equally advantageous.

In the embodiment wherein the nanostructures 330 are configured toprovide electrical and/or thermal coupling between the first substrate310 and the rough surface 340, the nanostructures 330 may be coated witha thin layer of gold or other material suitable for use as an electricaland/or thermal conductor. In an alternative embodiment, thenanostructures 330 may be coated with a thin layer of titanium/gold tovastly improve the thermal characteristics of the nanostructures 330.One skilled in the art will fully appreciate that many suitablematerials may be selected to achieve the desired electrical and/orthermal conductivity of the nanostructures. One skilled in the art willalso fully appreciate the processes that might be employed to make useof such electrical and/or thermal conductivity. For instance, vias maybe formed in the pliable surface 320 to provide electrical and/orthermal connection between the thin conductive layer and the firstsubstrate 310.

Positioned over the plurality of nanostructures 330, and in thisembodiment at least partially in contact with the plurality ofnanostructures 330, is the rough surface 340 having the degree ofsurface roughness. The rough surface 340 may comprise many differentmaterials and configurations while staying within the purview of thepresent invention. For instance, in the embodiment shown in FIG. 3 therough surface 340 is a package configured to protect the first substrate310 from external conditions. Accordingly, the plurality ofnanostructures 330 in the embodiment of FIG. 3 are configured to couplethe semiconductor chip (e.g., the first substrate 310), whether it bephysically, electrically, thermally or any combination thereof, to thepackage (e.g., the rough surface 340).

Advantageous to the present invention, the pliable surface 320 allowsthe plurality of nanostructures to at least partially conform to thedegree of surface roughness of the rough surface 340 when thenanostructures 330 come into contact therewith. In one embodiment, thepliable surface 320 is configured in such a way as to accommodate adegree of roughness of up to about several microns, while providing theappropriate connection between the nanostructures 330 and the roughsurface 340. In this embodiment, the appropriate connection may includean appropriate adhesion between the nanostructures 330 and the roughsurface 340, whether it is by way of intermolecular forces, Van DerWaals forces, dipole-dipole forces or another mechanism. The appropriateconnection may also include the appropriate conductive connectionbetween the nanostructures 330 and the rough surface 340, whether it iselectrical, thermal, or a combination thereof. Moreover, the appropriateconnection may be both an appropriate adhesive connection and anappropriate conductive connection.

The adhesion force resulting from the above-described contact isrelatively high since a large surface area of the nanostructures 330 isin contact with the rough surface 340. Such a high adhesion force is aresult of both the friction force resulting between the nanoposts aswell as intermolecular forces, such as well-known Van Der Waals forces,between the molecules of the nanoposts on the surface. Thus, adhesiveinterconnections suitable for use in connecting electronics componentsin electronics packages are formed.

Turning now to FIG. 4, illustrated is a cross-sectional view of analternative embodiment of an interconnect 400 manufactured in accordancewith the principles of the present invention. The interconnect 400 ofFIG. 4 is similar to the interconnect 300 of FIG. 3 with the exceptionthat the pliable surface 420 of FIG. 4 is different from the pliablesurface 320 of FIG. 3. Accordingly, reference numerals shared betweenFIGS. 3 and 4 indicate substantially similar features.

As is illustrated in FIG. 4, the pliable surface 420 of FIG. 4 includesone or more portions 425 etched there from. In this embodiment, theetched portions 425 may be used to provide increases flexibility of thepliable surface 420. For instance, in the embodiment above wherein thepliable surface 320 comprises a polymer, the etched portions 425 couldbe used to increase the flexibility of the already pliable polymermaterial. In an alternative embodiment, however, for instance anembodiment wherein the pliable surface 420 comprises a material that isless pliable than the polymer but has other advantageous features (e.g.,better electrical or thermal conductive properties than the polymermaterial), the etched portions 425 could be used to create flexurepoints, and thus increase the flexibility of the pliable surface 420.One particular material that might benefit greatly from the etchedportions 425, and thus the flexure points, might be silicon.

In the embodiment shown in FIG. 4, the etched portions 425 are locatedon an opposing side of the pliable surface 420 as the nanostructures330. In this embodiment, the location, frequency, size, shape, etc. ofthe etched portions 425 may vary greatly. For instance, the etchedportions 425 could be fully tailored for a specific purpose withoutsubstantial concern for the nanostructures 330 located on the opposingsurface of the pliable surface 420. One skilled in the art will fullyappreciate the processes that might be employed to create these etchedportions 425, including using conventional photolithography and etchingtechniques, among others.

Turning briefly now to FIG. 5, illustrated is a cross-sectional view ofan alternative embodiment of an interconnect 500 manufactured inaccordance with the principles of the present invention. Theinterconnect 500 of FIG. 5 is substantially similar to the interconnect400 of FIG. 4 with the exception that the etched portions 525 of theinterconnect 500 are located on a same side of the pliable surface 520as the nanostructures 330, as compared to the etched portions 425.Depending on the specifics of the pliable surface 520, the positioningof the etched portions 525 on the same side of the pliable surface 520as the nanostructures 330 may provide increased flexibility over thatillustrated in FIG. 4. Again, one skilled in the art will fullyappreciate the processes that might be employed to create these etchedportions 525, including the placement of the etched portions 525 betweenthe nanostructures 330.

Turning now to FIG. 6, illustrated is a cross-sectional view of analternative embodiment of an interconnect 600 manufactured in accordancewith the principles of the present invention. The interconnect 600 ofFIG. 6 is similar, at least in idea, to the interconnect 300 of FIG. 3.The interconnect 600 of FIG. 6, however, has its pliable surface 620coupled to and at least partially suspended over the first substrate310. In this embodiment, a gap between the pliable surface 620 and thefirst substrate 310 allows the pliable surface 620 to have improvedpliability.

The interconnect 600 of FIG. 6 may be manufactured a number of differentways while staying within the scope of the present invention. Forinstance, in one embodiment, the pliable surface 620 is at leastpartially suspended over the first substrate 310 by forming asacrificial spacer layer, such as silicon dioxide or silicon nitride,between the pliable surface 620 and the first substrate 310, and thenselectively removing the sacrificial spacer layer to release the pliablesurface 620 from the first substrate 310. In the embodiment shown, thepliable surface 620 is a thin layer of conductive material, such as athin (e.g., approximately 25 to 50 micrometers) aluminum layer. Whilenot illustrated, other materials and conventional techniques might alsobe used to form the interconnect 600 illustrated in FIG. 6.

Turning now to FIG. 7, illustrated is a cross-sectional view of analternative embodiment of an interconnect 700 manufactured in accordancewith the principles of the present invention. The interconnect 700 ofFIG. 7 includes a pliable surface 720 that may be similar to the pliablesurface 320 illustrated and discussed with respect to FIG. 3. However,the pliable surface 720 of FIG. 7 has a first plurality ofnanostructures 730 a disposed on one side of the pliable surface 720 aswell as a second plurality of nanostructures 730 b disposed on anopposing side thereof. In the embodiment shown, the first and secondplurality of nanostructures 730 a, 730 b are positioned so as tocomplement one another. It is believed that this complementary natureallows the first and second plurality of nanostructures 730 a, 730 b toaccommodate increased surface roughness of any substrate that they maycontact.

As is illustrated in FIG. 7, the first plurality of nanostructures 730 aare at least partially coupled to a first substrate 740 a and the secondplurality of nanostructures 730 b are at least partially coupled to asecond substrate 740 b. In the embodiment of FIG. 7, one or both of thefirst or second substrates 740 a, 740 b are a rough surface having adegree of surface roughness. Accordingly, the first and second pluralityof nanostructures 730 a, 730 b disposed on the pliable surface 720 areconfigured to at least partially conform to the degree of surfaceroughness of one or both of the first and second substrates 740 a, 740b. In contrast to the embodiments of FIGS. 3-6, the interconnect 700 ofFIG. 7 uses the nanostructures 730 a, 730 b, and the attractive forcesassociated therewith, to couple to the first and second surfaces 740 a,740 b, respectively. Those skilled in the art understand that processessimilar to those used to manufacture the interconnect 300 of FIG. 3could be used to manufacture the interconnect 700 of FIG. 7. Thus, nofurther detail is given.

Turning finally to FIG. 8, illustrated is a cross-sectional view of analternative embodiment of an interconnect 800 manufactured in accordancewith the principles of the present invention. The interconnect of FIG. 8includes a first substrate 810, a first pliable surface 820 coupled tothe first substrate 810, a first plurality of nanostructures 830 coupledto the first pliable surface, as well as a second substrate 840, asecond pliable surface 850 coupled to the second substrate 840 and asecond plurality of nanostructures 860 coupled to the second pliablesurface 850. In this embodiment, a surface roughness of the firstsubstrate 810 may ultimately be transferred to the first plurality ofnanostructures 830, and thus the second plurality of nanostructures 860coupled to the second pliable surface 850 are configured to at leastpartially conform to the surface roughness of the first plurality ofnanostructures 830. Just the same, a surface roughness of the secondsubstrate 840 may ultimately be transferred to the second plurality ofnanostructures 860, and thus the first plurality of nanostructures 830coupled to the first pliable surface 820 are configured to at leastpartially conform to the surface roughness of the second plurality ofnanostructures 860. Ultimately, the first and second plurality ofnanostructures 830, 860, interleave with each other, the first andsecond pliable surfaces 820, 850, allowing the effects of any surfaceroughness of the first and second substrates 810, 840 to besubstantially reduced.

Although the present invention has been described in detail, thoseskilled in the art should understand that they can make various changes,substitutions and alterations herein without departing from the spiritand scope of the invention in its broadest form.

1. An interconnect, comprising: a pliable surface having a plurality ofnanostructures disposed thereon, the pliable surface configured to allowthe plurality of nanostructures to at least partially conform to asurface when the nanostructures come into contact therewith.
 2. Theinterconnect as recited in claim 1 wherein the pliable surface is asubstrate having portions etched there from to provide increasedflexibility.
 3. The interconnect as recited in claim 2 wherein theetched portions are located on an opposing side of the pliable surfaceas the nanostructures.
 4. The interconnect as recited in claim 2 whereinthe etched portions are located on a same side of the pliable surface asthe nanostructures, the etched portions positioned between thenanostructures.
 5. The interconnect as recited in claim 1 wherein thepliable surface is coupled to and at least partially suspended over asubstrate.
 6. The interconnect as recited in claim 1 wherein the pliablesurface comprises a polymer.
 7. The interconnect as recited in claim 1wherein a conductive connection exists between the nanostructures andthe surface.
 8. The interconnect as recited in claim 7 wherein theconductive connection is thermal, electrical or both thermal andelectrical.
 9. The interconnect as recited in claim 1 wherein theplurality of nanostructures are a first plurality of nanostructuresdisposed on a side of the pliable surface, and further including asecond plurality of nanostructures disposed on an opposing side of thepliable surface.
 10. The interconnect as recited in claim 9 wherein thesurface is a first surface and further including a second surface, andwherein the pliable surface is configured to allow the first pluralityof nanostructures to at least partially conform to the first surface andthe second plurality of nanostructures to at least partially conform tothe second surface.
 11. The interconnect as recited in claim 10 whereinattractive forces help at least a portion of the first plurality ofnanostructures adhere to the first surface and at least a portion of thesecond plurality of nanostructures adhere to the second surface, thefirst and second surfaces being coupled to one another.
 12. Theinterconnect as recited in claim 1 wherein attractive forces help atleast a portion of the plurality of nanostructures adhere to thesurface.
 13. The interconnect as recited in claim 12 wherein theplurality of nanostructures are a first plurality of nanostructures andthe surface is a second plurality of nanostructures.
 14. Theinterconnect as recited in claim 12 wherein the attractive forces areselected from the group consisting of: intermolecular forces; Van DerWaals forces; and dipole-dipole forces.
 15. The interconnect as recitedin claim 1 wherein the surface is a rough surface having a degree ofsurface roughness, and the pliable surface is configured to allow theplurality of nanostructures to at least partially conform to the roughsurface.
 16. A method for interconnecting multiple surfaces, comprising:contacting a plurality of nanostructures disposed on a pliable surfacewith a surface, wherein the pliable surface is configured to allow theplurality of nanostructures to at least partially conform to thesurface.
 17. The method as recited in claim 16 wherein attractive forceshelp at least a portion of the plurality of nanostructures adhere to thesurface.
 18. The method as recited in claim 16 wherein a conductiveconnection exists between the nanostructures and the surface.
 19. Themethod as recited in claim 18 wherein the conductive connection isthermal, electrical or both thermal and electrical.
 20. The method asrecited in claim 16 wherein the surface is a rough surface having adegree of surface roughness, and the pliable surface is configured toallow the plurality of nanostructures to at least partially conform tothe rough surface.